Central extensions of the Ptolemy-Thompson group and quantized Teichmuller theory

Louis Funar; Vlad Sergiescu

doi:10.1112/jtopol/jtp033

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arXiv · 0802.2996

Central extensions of the Ptolemy-Thompson group and quantized Teichmuller theory

Louis Funar·Vlad Sergiescu

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Abstract

The central extension of the Thompson group $T$ that arises in the quantized Teichmüller theory is 12 times the Euler class. This extension is obtained by taking a (partial) abelianization of the so-called braided Ptolemy-Thompson group introduced and studied in \cite{FK2}. We describe then the cyclic central extensions of $T$ by means of explicit presentations.

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Louis Funar, Vlad Sergiescu. 2009-10-23. Central extensions of the Ptolemy-Thompson group and quantized Teichmuller theory. https://doi.org/10.1112/jtopol%2Fjtp033

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